In the steam turbine art, there may be a single rotor with peripheral vanes against which the steam, entering the housing in a tangential direction, is directed. Where there are a plurality of rotors, they are customarily secured in spaced relation along a common shaft with stationary steam reversing blades therebetween. The steam is thus directed successively to all of the rotors to make maximum use of the available energy.
As far as I am aware, the prior art does not disclose the practice of directing one or two sources of steam simultaneously and tangentially at the vanes of two closely adjacent rotors in which one rotor is mounted directly on the turbine shaft and the other rotor is connected to the shaft by gearing. Further, the prior art does not disclose two side by side rotors running at different speeds in which the vanes on the rotors and housing are so arranged that the rotors are driven by both the kinetic energy of the steam against the vanes and the subsequent expanding force of the steam acting against the vanes.